Impact switch



April l, 1941!.. o. E. GRIGSBY `IMPACT swI'rcH Filed April 17, 1939 I l l l l l Patented Apr. 1, 1941 UNITED STATES PATENT OFFICE nurac'r swrrcn Owen E. Grixsby, Park Ridge, Ill. Application April 17, 1939, sern1No.gss,s1s

(c1. zoo- 52) 2Claims.

This invention relates to an impact switch and has particular application to automobiles, trucks, airplanes and the like. It is understood, of course, that the switch may be used in connecftion with other devices and for other purposes.

It is desirable to have automatic means for cutting off the ignition system on an internal combustion engine on vehicles and planes in the event lof an accident. Thus, on trucks Ait is old to have a mercury switch in the ignition circuit which is adapted to open said circuit in the event of a sudden stopping or overturning of the vehicle. Such switches, however, are unsatisfactory for the reason that a. series of impacts mayl reset the switch and undo the effect of the first impact. Furthermore, -such switches are dimcult to control and have been operated in many instances when the vehicle stops or starts suddenly or happens to go over some rough portion of the road. Under these conditions it is evident that operation of al switch of this character is not desired.

It is also desirable in many instances to have an impact switch operate some kind of an alarm in the event of an accident.

' The switch described herein is particularly adapted for the above purposes since itmay be adjusted to operate as the result of impacts of predetermined violence. Furthermore, the switch described herein will remain in its set position until changed by an impact and thereafter will not be returned to its reset position unless manually reset. The switch is simple and compact and may be set and reset in an easy and quick manner. Referring to the drawing:

.` Fig. 1 shows the switch in its case;

,Fig. 2 is a section on line 2-2 of Fig. l;

" Fig. 3 is a view similar to Fig. 2 but showing the switch tripped after an impact; y

Fig. 4 is a section similar to Fig. 2 but showing a modified form of switch; and

Fig. 5 is a section of the switch of Fig. 4 with the switch in tripped position.

The switch comprises a-base I of any suitable rigid material which may be either metal or insulation. In the particular case shown base l0 is of metal. This base has provided a. pair of apertures II and I2 in which bolts I3 and I4 are insulatingly mounted. Disposed on the inside of base I0 is an insulating block I5 suitably apertured, through which bolts I3 and I4 project. Rigidly carried by bolts I3 and Il and insulating block I are a pair of fixed contact members I'I and ii. Beyondcontact members I1 and I8 bolts I3 and Il are provided with'spacing nuts I9 and Cil and then pass through suitable apertures in an insulating block 2|. The block 2| is suitably apertured at the center at 22v and may be provided with a metal bushing 23'.

Disposed within aperture 22 of insulating block 2l is a. plunger 25 preferably having the same cross-section as the aperture 22 and longitudinally movable within said aperture. Plunger 25 at the inner end thereof is provided witha fiaiing contact portion 25 of brass or other conducting material. As is clearly seen in Fig. 2, contact portion 26 is adapted to function as a movable contact and bridge thegap between stationary contacts II and I8.

Plunger 25 is provided with a recess 28 at the contact end thereof and within this recess' a spring 29 is disposed. This spring bears against insulating strip I5 and, in order to maintain the spring properly centered, it is preferred to provide a. small vrecess 30 in insulating strip I5. Preferably the outer end 3I of plunger 25 is cupped as shown in Fig. 2. Y

Supported by base I0 is a casing 32 of any suitable material such as metal. This casing 32 is provided with an aperture 33 opposite the plunger 25. A rubber grommet 35 is disposed in aperture 33 and through this a pin 36 is disposed. 'I'he outer end of pin 35 carries a knob 31 While the inner end carries a heavy inertia member 40 made of any suitable material such as iron, lead or brass if necessary. This member may have any desired shape and as shown is provided with a projecting head portion 4I adapted to fit into cup 3l of the plunger and a skirt portion 42 where the weight of the member is concentrated. A coil spring 45 is disposed around pin 36 and extends between weight 40 and a washer 4l around pin 36 bearing against grommet 35.

Bolts I3 and I4 are suitably insulated in the base I0 if the latter is metal by spacing as shown in the drawing and may be provided with binding terminals as shown.

Upon suflicient impact the heavy member 40 will be displaced from its normal position of Fig.

' 2 t'o the position shown in Fig. 3thus permitting the movable contact member 26 to spring away and open the circuit. In order to reset the switch it is merely necessary to pull back plunger 36 by means of knob 3l and dispose member 40 in position as shown in Fig. 2.

The structures shown in Figs. 4 and 5 are l generally similar to thev structures shown in Figs. 2 and 3 with the exception that the stationary contact members I1' and I8' are disposed against E v aaaaeva insulating block 2i so that normally the switch is open and will be closed upon impactas shown in Fig. 5.

The characteristics of the device may be conl trolled by the mass and shape of weight 40,- tension of spring 135 and depth of cupped end 3i. It is preferred to have skirt 42 so shaped that negligible cam action will occur against cupped member 25 tending to overcome spring 29. By

having the angle between the sides and pin axisY as small as possible, the tendency of the Weight to straighten will merely exert a side thrust on cupped member 25. Any desired shape of weight may be used.

I claim:

1. An impact switch comprising a cup-shaped member and a detachable at cover member cooperating to form a hollow enclosed chamber, a switch assembly mounted on one of said members, said switch assembly includingstationary and movable contacts having open and closedY positions and including a spring means for biasing said switch assembly to one of its two positions, said other member having an aperture opposite said spring means, a pin loosely mounted in said aperture, said pin having a. knob on the outer end thereof and a weight on the inner end thereof, a coil spring around said pin between said other rnember and weight for spring biasing said pin and weight to an innermost position in said chamber, said weight and spring means having intertting surfaces whereby said switch may be set .by pulling said pin outwardly against its spring to set the interfitting surfaces against .each other, said pin bias being sufficiently strong to overcome the switch assembly spring bias and set the switch to its other position, said impact switch having suicient stability to remain in this set position until a shock to the structure occurs whereupon the weight is deflected from its set position to release the switch assembly.

2; The structure of claim 1 wherein said fiat cover member carries the switch assembly and wherein the cup member is apertured and has a rubber grommet through which said pin projects.

OWEN E. GRIGSBY. 

